Slurry processing for black oil conversion

ABSTRACT

A catalytic slurry process for converting a hydrocarbonaceous charge stock containing hydrocarbon-insoluble asphaltenes. The slurry consists of the fresh feed charge stock, hydrogen, a recycled diluent boiling above about 950* F. and from 1.0 percent to about 25.0 percent by weight of finely divided catalyst particles. Separation of the catalyst, from the total reaction product, is effected through the use of a foam chamber and foam breaker. Preferred catalysts are the unsupported sulfides of the metals from Groups V-B, VI-B and VIII, with vanadium sulfide being particularly preferred.

United States Patent Edward S. Rogers IIinsdale;

Edward IIorvath, Hickory Hills, both of III. 885,857

Dec. 17, 1969 Nov. 2, 1971 Universal 011 Products Company Des Plaints, Ill.

[72] Inventors Appl. Nov Filed Patented Assignee SLURRY PROCESSING FOR BLACK OIL CONVERSION 6 Claims, 1 Drawing Fig.

US. Cl 208/97, 208/112, 208/251 H, 208/309 Int. Cl C10g 13/00 Field of Search 208/97, 112,251H, 309

Mixing Zane 1 Charge Slack Catalyst Fa am Chamber Raacl/an Gail [56] References Cited UNITED STATES PATENTS 3,331,769 7/1967 Gatsis 208/309 3,429,801 2/1969 Gleim et al. 208/97 3,437,584 4/1969 l-Iamblin 208/97 Primary Examiner-Herbert Levine Attorneys-James R. l-loatson, Jr. and Robert W. Erickson ABSTRACT: A catalytic slurry process for converting a hydrocarbonaceous charge stock containing hydrocarbon-insoluble asphaltenes. The slurry consists of the fresh feed charge stock, hydrogen, a recycled diluent boiling above about 950 F. and from L0 percent to about 25.0 percent by weight of finely divided catalyst particles. Separation of the catalyst, from the total reaction product, is effected through the use of a foam chamber and foam breaker. Preferred catalysts are the unsupported sulfides of the metals from Groups V-B, VI-B and VIII, with vanadium sulfide being particularly preferred.

3 F n 0G!" Breaker Separation Zane Gala/ys! Recovery SLURRY PROCESSING FOR BLACK OIL CONVERSION The process described herein is adaptable to the conversion of petroleum crude oil residuals having a high metals content and comprising a hydrocarbon-insoluble asphaltene fraction; the latter constitutes high molecular weight material insoluble in light hydrocarbons such as pentane or heptane. More specifically, our invention is directed toward a method for cffecting a catalytic slurry process in the presence of hydrogen, in order to convert atmospheric tower bottoms, vacuum columnbottoms, crude oil residuum, topped and/or reduced crude oils, coal oil extracts, crude oils extracted from tar sands, etc., all of which are commonly referred to in the art as black oils.

Petroleum crude oils, and particularly the heavy residuals therefrom, contain sulfurous compounds in exceedingly large quantities, nitrogenous compounds, high molecular weight organo-metallic complexes principally comprising nickel and vanadium as the metallic component, and hydrocarbon-insoluble asphaltic material. The latter is generally found to be complexed with sulfur, and to a certain extent, with the metallic contaminants. A black oil is generally characterized as being a heavy hydrocarbonaceous material of which more than about l0.0 percent (by volume) boils above a temperature of about l,050 F. (referred to as nondistillables) and which further has a gravity less than about 20.0 API. Sulfur concentrations are exceedingly high, most often greater than 2.0 percent by weight. Conradson carbon residu factors usually exceed 1.0 percent by weight and the concentration of metals can range from as low as 20 p.p.m. to as high as about 750 p.p.m.

The process encompassed by our invention is particularly directed toward the conversion of those black oils severely contaminated by considerable quantities of hydrocarbon-insoluble asphaltenes. Although asphaltenes are nondistillable, it should be noted that all nondistillables are not asphaltenes. Generally, those hydrocarbons having normal boiling points above about l,050 F. are designated nondistillables," regardless of whether they are asphaltic in nature.

Specific examples of the charge stocks to which the present invention is applicable include a vacuum tower bottoms product having a gravity of 7.1 API. and containing 4.1 percent by weight of sulfur and 23.7 percent by weight of asphaltenes; a topped Middle-east crude oil having a gravity of ll.0 API and containing about 10.1 percent by weight of asphaltenes and 5.2 percent by weight of sulfur; and, a vacuum residuum having a gravity of 8.8 APl, containing 3.0 percent by weight ofsulfur and 4,300 p.p.m. of nitrogen.

The utilization of our invention affords the conversion of such material into distillable hydrocarbons, heretofore having been considered virtually impossible to achieve on a continuous basis with an acceptable catalyst life. The principal difficulty, encountered in a fixed-bed catalytic system, resides in the lack of sufi'icient catalyst stability in the presence of such relatively large quantities of metals-Le. from about 150 p.p.m. to as high as 750 p.p.m. computed as the element-and additionally from the presence of large quantities of asphaltenic material and other nondistillables. The asphaltenic material comprises high molecular weight coke precursors, insoluble in light normally liquid hydrocarbons such as pentane and/or heptane. It is generally found to be dispersed within the black oil, and, when subjected to elevated temperature, has the tendency to flocculate and polymerize whereby conversion to more valuable oil-soluble products becomes extremely difficult.

OBJECTS AND EMBODlMENTS A principal object of our invention is to convert hydrocarbonaceous black oils into lower boiling hydrocarbon products.

Another object is to provide a catalytic slurry process for black oil conversion, facilitating the means by which catalyst particles are separated from the conversion product effluent.

Therefore, the present invention afiords a process for the conversion of an asphaltene-containing hydrocarbonaceous charge stock which comprises the steps of: (a) admixing said charge stock, hydrogen and a finely divided catalyst containing at least one metal component from the metals of Groups V-B, Vl-B and Vlll, to form a reactive slurry; (b) reacting said slurry in a cracking reaction zone, or coil, at a pressure above about 500 p.s.i.g. and a temperature above about 800 F.; (c) depressuring the resulting cracked product efi'luent into an elongated foam chamber, at a pressure below about p.s.i.g.; and, (d) removing a catalyst-containing foam and unconverted asphaltenes from the upper portion of said chamber and recovering a substantially asphaltene-free hydrocarbon fraction from the lower portion thereof.

In another embodiment, the foam is introduced into a foam breaker and therein separated into a hydrogen-rich gaseous phase and an asphaltene/catalyst phase.

Other objects and embodiments of our invention relate to processing techniques and preferred operating conditions, and suitable catalytic composites and the concentration thereof. These will become evident from the following detailed description of the process encompassed by our invention.

SUMMARY OF INVENTION The particular finely divided, solid catalyst utilized in the present slurry process, is not considered to be an essential feature. However, it should be recognized that preferred catalytically active metalic components of the catalyst possess both cracking and hydrogenation activity. Thus, in accordance with The Periodic Table of The Elements, E. H. Sargent and Co., 1964, the catalytically active metallic component will be selected from the metals of Group V-B, Vl-B and VIII of the Periodic Table. Of these, preferred metallic components are vanadium, chromium, iron, cobalt, nickel, niobium, molybdenum, tantalum and/or tungsten; although suitable, the noble metals of Group V111 are not generally considered for use in a slurry-type process for obvious economic considerations. These catalytically active metallic components may be combined with an inorganic oxide carrier material such as alumina, silica, zirconia, magnesia, boria and mixtures including alumina-silica, alumina-zirconia, alumina-silica-boron phosphate, etc. Regardless of the method of preparing the catalyst, the final composite will be ground to a finely divided state. However, recent developments in catalytic slurry processing have indicated that the unsupported sulfides of the foregoing metals, and particularly those of Group V-B, offer more advantageous results. For this reason, the preferred catalyst comprises unsupported tantalum, niobium and vanadium sulfides, the latter being particularly preferred. In the interest of brevity, the following discussion will be limited to the use of vanadium sulfides as the catalyst employed in the present slurry process.

The vanadium sulfides may be prepared in any convenient manner, the precise method not being essential to the present invention. For example, vanadium pentoxide may be reduced with sulfur dioxide, sulfuric acid and water to yield a solid hydrate of vanadyl sulfate. The latter is treated with hydrogen sulfide at a temperature of about 300 C. to produce the vanadium sulfide slurried into the system.

The concentration of vanadium sulfides slurried with the hydrocarbonaceous material V,to the reaction chamber, is within the range of from about 1.0 percent to about 25.0 percent by weight, calculated as the elemental metal. Excessive concentrations do not appear to enhance the results, even with extremely contaminated charge stocks having exceedingly high asphaltene concentrations. Preferred concentrations of vanadium sulfides are within the range of from about 2.0 percent to about 15.0 percent by weight. It should be noted that vanadium forms a multiplicity of sulfides, some of which are nonstoichiometric. Examples of various sulfides of vanadium include VS, V8,, V 5 V8,, VS, and V,S,. During the reaction, the vanadium sulfide, prepared as hereinabove set forth. is convened to one or more of these forms, or some other form.

The charge stock is admixed with hydrogen in an amount of from 1,000 to about 50,000 s.c.f./bbl. and from 1.0 percent to about 25.0 percent by weight of finely divided vanadium sulfide, as elemental vanadium. Preferably, the hydrogen concentration is in the range of 3,000 to about 20,000 s.c.f./bbl. and the quantityof catalyst is 2.0 percent to about 15.0 percent by weight. The mixture is introduced into a reaction zone, or coil, at a pressure in the range of 500 to about 3,000 p.s.i.g. and a temperature above about 800 F. preferred temperatures being in the range of 825 F. to about l,000 F. In a preferred embodiment, a portion of the distillable product effluent'is recycled to the mixing zone in an amount which provides a combined liquid feed ratio of 1.1 to about 6.0.

Residence time within the reaction zone, or coil, is dependent upon a multitude of considerations. These considerations involve temperature, the degree of mixing, catalyst concentration, charge stock characteristics, degree of conversion and the combined liquid feed ratio. In most applications of our invention, the residence time will range from about 30 seconds to about 4 minutes-The reaction product effluent is depressured into a foam chamber at a pressure of about l to about 500 p.s.i.g. Generally, the foam chamber will be an elongated vessel equipped with a turbine mixer, and the effluent will enter through a locus in the lower portion thereof. The par ticular construction of the chamber is not an essential feature of our invention; however, it is a preferred technique to introduce the efiluent through a sparger assembly. The pressure drop which occurs across the sparger nozzles permits the dissolved hydrogen to come out of solution. The hydrogen bubbles nucleate at the large unconverted asphaltene molecules, and at the catalystparticles, carrying them, to the upper foam section of the chamber. The asphaltene/catalystfoam is continuously displaced by the entering slurring, a passes into a suitable foam breaker. One such suitable foam breaker is in the form of a rotary vacuum filter. Foam is discharged into the filter feed pan and is drawn up against the filter medium. This breaks the foam and releases the hydrogen into the inner portion of the filter drum. The hydrogen is recycled, via compressive means, in admixture with makeup hydrogen, to the mixing zone.

Substantially aspaltene-free distillable hydrocarbons are withdrawn from the lower portion of the foam chamber and in part recycled to the mixing zone. The asphaltenc/catalyst sludge collected on the filter is removed to a separation zone wherein entrained distillables are removed. Suitable solvents, for removing the residual distillable hydrocarbons, include heptane, pentane, etc. The solvent and distillables are then combined with that portion of the normally liquid reaction zone effluent not being recycled, the mixture constituting the product of the process. The remainder of the sludge is sent to a catalyst recovery system. In a preferred embodiment, from about 75.0 percent to about 95.0 percent by weight of the sludge is recycled to the mixing zone. Catalyst is easily recovered by burning the sludge in air; this results in vanadium pentoxide. Reduction with sulfur dioxide, sulfuric acid and water produces vanadyl sulfate. The procedure then follows the previously described technique for the preparation of fresh vanadium sulfide.

DESCRIPTION OF DRAWING The accompanying drawing is a simplified flow diagram illustrating one embodiment of our invention. In the drawing, various valves, pumps, compressors, startup lines, heatrecovery circuits and other miscellaneous appurtenances have been eliminated as not being essential to an understanding of the invention. The use of such hardware is well within the purview of one having expertise in petroleum-refining operations and techniques. lt is understood that the drawing is presented for illustrative purposes only, and is not considered limiting the scope ofour invention.

The charge stock, for example a reduced crude oil containing about 10.0 percent by weight of asphaltenes, is introduced by way of line 1 into mixing zone 7. Recycle hydrogen from line 3 is admixed with makeup hydrogen in line 2, and passed thcrethrough into the mixing zone. The hydrogen concentration is about [0,000 s.c.f./bbl., and the fresh feed capacity is about 30,000 bbl./day. A finely divided vanadium sulfide catalyst is admixed with about 30,000 bbl./day of a recycled diluent in line 5, containing recirculated catalyst from line 6, the catalyst concentration being about 10.0 percent by weight; the mixture enters mixing zone 7 by way of line 4.

The entire reactive slurry, at a temperature of about 900 F. and under a pressure of about l,500 p.s.i.g., enters reaction coil 9 through line 8, the reaction product effluent being withdrawn through line 10 and introduced thereby into foam chamber 11 at a reduced pressure of l00 p.s.i.g. Foam chamber 11 is equipped with sparger nozzles in its lower portion and a turbine mixer, neither of which is illustrated in the drawing. The foam is created as the product effluent is depressured through the sparger nozzles. Normally liquid, distillable hydrocarbons, substantially asphaltene-free, are removed from foam chamber 11 through line 14. The recycled diluent is diverted through line 5 in an amount of about 30,000 bbL/day, thereby providing a combined liquid feed ratio of 2.0:l.0. Combined liquid feed ratio is herein defined as the total volume of normally liquid material charged to the mixing zone per volume of fresh feed charge stock.

An asphaltene/catalyst foam is continuously withdrawn via line 12 into foam breaker 13. In this illustration foam breaker 13 is a vacuum filter, from the drum of which hydrogen is recycled through line 3. The asphaltene/catalyst sludge is removed from the filter medium through line 15 into separation zone 16. The sludge is washed with n-heptane to remove residual distillables which are withdrawn through line 17 and combined with the distillable product in line 14. The asphaltene/catalyst concentrate is removed from separation zonelo through line 6. About 85.0 percent by weight of the concentrate is recycled through line 6 to the mixing zone, the remaining 15.0 percent being diverted through line 18 to a catalyst recovery system.

The foregoing specification indicates the means by which the process of the present invention is conducted. In the illustration, about 28,l00 bbL/day of distillable, asphaltene-free product is obtained.

We claim as our invention:

1. A process for the conversion of an asphaltene-containing hydrocarbonaceous charge stock which comprises the steps of:

a. admixing said charge stock, hydrogen and a finely divided catalyst containing at least one metal component from the metals ofGroups V-B, Vl-B, and VIII, to form a reactive slurry;

b. reacting said slurry in a cracking reaction zone. or coil, at a pressure above about 500 p.s.i.g. and a temperature above about 800 F.,

c. depressuring the resulting cracked product effluent into an elongated foam chamber, at a pressure below abou500 p.s.i.g.; and,

d. removing a catalyst-containing foam and unconverted asphaltenes from the upper portion of said chamber and recovering a substantially asphaltene-free hydrocarbon fraction from the lower portion thereof.

2. The process of claim I further characterized in that said foam is introduced into a foam breaker and therein separated into a hydrogen-rich gaseous phase and an asphaltene/catalyst phase.

3. The process of claim 2 further characterized in that said asphaltene/catalyst phase is separated to provide distillable hydrocarbons and an asphaltene/catalyst concentrate.

4. The process of claim 3 further characterized in that said concentrate is in part recycled to combine with said charge stock.

5. The process of claim I further characterized in that sai: '6, Tie pr ci af'l a im 5 Either characterized ih tha: s aid catalyst is a sulfide of at least one metal from Groups V-B, catalyst isavanadium sulfide. Vl-B and V1". 1. i a i e 

2. The process of claim 1 further characterized in that said foam is introduced into a foam breaker and therein separated into a hydrogen-rich gaseous phase and an asphaltene/catalyst phase.
 3. The process of claim 2 further characterized in that said asphaltene/catalyst phase is separated to provide distillable hydrocarbons and an asphaltene/catalyst concentrate.
 4. The process of claim 3 further characterized in that said concentrate is in part recycled to combine with said charge stock.
 5. The process of claim 1 further characterized in that said catalyst is a sulfide of at least one metal from Groups V-B, VI-B and VIII.
 6. The process of claim 5 further characterized in that said catalyst is a vanadium sulfide. 